Process for making extended surface convectors



w. E. oAKEY I PROCESS FOR MAKING EXTENDED SURFACE CONVECTORS July 2, 1935.

File@ Jan. 9, 1931 @5% M www Patented July '2, 1935 UNITED STATES PROCESS FOR vMAKING EXTENDED SURFACE CONVECTORS William E. Oakey, Oriskany, N. Y.

' Application January 9, 1931, Serial No. 507,559

6 Claims.

My invention relates to heating and cooling apparatus and particularly to the manufacture of convectors of the extended surface type.`v

In certain forms of heating and cooling de- 5. vices of the extended surface type it is customary to provide theconductor, such as a tube or tubes. through which the heating or cooling fluids pass, with a series of plates or fins the surfaces of which, in efl'ect, constitute extensions of the :heat transfer surface of the conductor. Such plates or fins are often assemblea on the conducting tube by pressing the tube through openings formedtherefor inthe' fins, the fins being held in place on the tube by'friction, and, in some cases, by subsequently soldering the fins to the tubes.

It is desirable that an effective bondV be provided between the conducting tube and the fins mounted thereon both to increase the effectiveness of the heat transfer of theheatin-g or cooling device and also to provide a rigid structure. It is also desirable to protect the surfaces of the heating or cooling device against deterioration.

A feature of my invention resides in the provision of an effective conducting bond between a conducting tube or tubes and the plates or fins whose Vsurfaces constitute extensions of the sur-v also serves to improve the appearance of the unit.

A fourth feature of my invention resides in providing the conducting bond, securing the fins to the conductors and applying the protecting and finishing coating in a single operation.

Other features and advantages ofmy invention willbecome apparent upon consideration of the following detailed description and the ap?- pended claims taken in conjunction with the accompanying drawing. In the Adrawing:- 1igu1'e 1 is a plan view o a heating or cooling unit constructed in accordance withmyinvention, Y Figure 2 is a side elevation, partially in section of a portion of the unit shown in Figure 1, and Figure 3 is a view in elevation of one of the plates or nnsrof the convector unit and shows one of the fluid conductor tubes in section.

Referring to Figures 1, 2 and 3, the heating or cooling unit l comprises seamed, or seamless,

steel tubes 2 pressed into openings 3 provided therefor in headers 4, which may be of gray or malleable iron or sheet steel. Each header 4 is formed with an interior chamber 5 communicating with the tubes 2 and is also provided with a 5 suitable port 6 forconnecting the unit in the heating or cooling system. Mounted on the tubes 2 between the headers 4 is a series of plates or ns l, the surfaces of which, in effect, constitute extensions of the surfaces of the tubes. 10

Each of the nsl, one of which is shown in elevation in Figure 3, comprises a plate, which maybe of sheet steel, provided with openings 8 for the tubes 2. Bosses I0 are provided on the fins adjacent the 'openings 8, as by extrusion of 15 the fin in forming the openings. The ns l are supported in spaced relation, as in jigs. and the tubes 2 are then pressed through the bosses I0 and openings 8 in the fins to assemble the fins in spa-ced relation on the tubes. The tubes 2 20 with*` the flns 1 thereon are then combined with the headers 4 by pressing the ends of the tubes into the openings 3 provided in the headers.

When the fins, tubes and headers are thus assembled into a heating or cooling unit, the unit 25 may then be dipped as a whole into a suitable flux bath. The heating unit is then dipped into and movedl about in a brazingbath of molten brass. The molten brass adheres to the exterior surfaces of the nsl, tubes 2 and headers 4, 3 and also to the interior surfaces of the tubes 2 and headers 4, thus affording a coating for protecting these surfaces against rusting and the possible 'deteriorating action of the heating or refrigerating fluids. 35

- The molten brass also acts to braz'e the ns 1 to the tubes 2 and the tubes to the headers 4, the molten brass flowing into all spaces between the fins and tubes and the tubes and headers, as indicated at I6 and I'l in Figure 2. The brazing 40 metal not only serves to braze the fins rigidly to the tubes but also forms an effective conducting -bond between the tunes` and fins.

The brass coating thus provided on the surfaces of the fins, tubes and headers forms a shell, 45 as indicated by the irregular line I8 in Figure 2, within which theheaders 4, tubes 2 and fins 'i are imbedded. Vlewed in another light, the nished heating and cooling unit my be considered a cast brass convector produced by dipping a core made up of the headers, tubes and fins into molten brass, the core in the casting operation becoming rmly imbedded within a brass shell. The exterior surfaces of this shell form a continuous heat transfer surface, thereby increasing the em- A `iency of the heating or cooling-unit Since the brass shell is a very good conductor.

It is to be noted that by brazing the ns to the tubes and the tubes to the headers, as above described, a perfect metallic joint is formed between the ilns and tubes and the tubes and headers. This metallic joint forms a better conducting bond than when the fins are held on the tubes by asoldered joint or by friction. Solder is a poor heat conductor and soldered joints are liable to oxidation, which may act as an insulator at the joints thus impairing the effectiveness of the solder as a conducting bond between the tubes and ns. When the ns are held on the tubes by friction the resulting joint does not form an eilicient conducting bond between the tube and ns. A friction joint is particularly disadvantageous if the convector unit is immersed in a uid to heat or cool the latter. Such immersion results in rusting at the joints, thus insulating the fins from the tubes and destroying whatever conductive qualities friction joints might possess.

It is also to be noted that by brazing the ns to the tubes and the tubes to the headers a stronger connection is provided between these parts than may be obtained` by soldering these parts to each other, since the brazing metal unites the various parts into an integral whole. The ns, tubes and headers are more rigidly and permanently secured to one another by a brass brazing than by soldered connections since the brazing brass is not subject to fatigue, due to expansion or contraction as a consequence of the ow of heating or cooling fluids as soldered connections are. As a result. the ns and other parts of the heating or cooling unit are less apt to be twisted or otherwise distorted when the unit is installed in a heating or cooling system.

The joining of the tubes to the headers by the brazing metal also provides a fluid-tight joint between these parts, which joint is superior to a friction joint, or a soldered joint, since fatigue of the solder may result in leakage.

Inasmuch as dipping the 'assembled parts of the the tubes, fins and headers to one another, provides an eective Iconducting bond between the tubes, fins and headers, and applies a rust-proof coating to the interior and exterior surfaces of the unit, all in'a single operation, the manufacturing costs of such units are appreciably reduced. Since' a brass coating is applied to the exterior surfaces of the heating or cooling unit, it is unnecessary to subsequently glld or paint the unit to secure a pleasing appearance when the conditions of installation so require. As afresult the manufacturing costs are further reduced.

Although I have described -my invention in connection with a convector unit having, a pair of conducting tubes it is to be understood that my invention is equally applicable to a convector unit having only a single conducting tube or one having more than two tubes.

It will be apparent from the foregoing description that a heating or cooling unit constructed in accordance with the principles of my invention is eiiicient in operation, rigid in construction, neat in appearance and may be economically manufactured.

While my invention is described above in its preferred form, there are many changes and variations which may be made without departing 'from the spirit thereof, and I desire to include all such changes and variations within the scope of the appended claims.

I claim:

l. The method of manufacturing a convector which comprises assembling a series of sheet metal ns of small area on a conducting tube, assembling headers to the ends of the tube, and dipping the assembled unit in liquid brass to form a metallic bond between the fins and the tube and between the tube and the headers and to imbed the tube, ns and headers'within a brass shell which forms an effective conducting and protective surface for the unit.

2. The method of manufacturing a convector having a. conductor tube connected at each end to a header and provided with a series of sheet metal fins of small area thereon ythe surfaces of which constitute extensions of the surface of the tube, which comprises mounting the fins on the tube, assembling the tube to the headers and dipping the assembled unit in liquid brass to imbed the tube, fins and headers within a brass shell having a continuous heat conducting surface.

3. The method of manufacturing a convector which comprises assembling a series of ferrous sheet metal fins of'small area on a conducting ferrous metal tube. assembling a ferrous metal header on each end of the tube, and dipping the assembled unit in a molten brazing bath to form a metallic bond between the ns and the tube and between the tube and the headers and to applyV a protective and finishing coating to all the exterior and interior surfaces of the convector.

4. The method of manufacturing a convector which comprises assembling a series of sheet metal ns of small area on a conducting tube land dipping the assembled unit in liquid brass to heating or cooling unit in liquid brass secures form a metallic bond between the fins and the tube and to imbed the tube and ns within a brass shell which forms an effective heat conducting, and protective surface for the unit.

5. The method of manufacturing a convector having a conductor tube provided with a series of sheet metal fins of small area thereon, the surfaces of which constitute extensions of the surface of the tube, which consists in mounting the fins on the tube, and dipping the assembled unit in liquid brass to imbed the tube and fins within a brass shell havingA a continuous heat conducting surface.

6. The method of manufacturing a convector which comprises assembling a series of ferrous sheet metal ins of small area on a conducting ferrous metal tube, and dipping the assembled unit in a molten brazing bath to form a metallic bond between the fins and the tube and to apply a protective and finishing coating to all the exteriox' and interior surfaces of the unit.

WILLIAM E. OAKEY. 

